Boring needle devices of the type above mentioned are known which have effective needle length adjustable without use of any adjustment expedient, and one example thereof is provided with an annular member of an elastomeric material, such as rubber, etc., having its center aperture through which extends the needle and thus fitted on the needle snugly by action of elasticity of the material to be shiftable for adjustment of an effective needle length. The other example has double nuts meshingly fitted on the needle, with thread being formed thereon, to be displaced for adjustment of an effective needle length. In the first mode, the annular member is subject to flexure deformation by contours of the top faces of teeth, or to rotational friction generated by the tooth top faces with which the annular member is abuttingly in contact, so that the needle is differentially turned in the center aperture of the annular member, with the annular member being lifted along the needle. The mode has the disadvantage that an effective needle length once defined by position of the annular member is likely to inadvertently vary, lacking satisfactory preciseness. The second mode above is disadvantageous in involving burdensome, awkward manipulation of positioning the double nuts to adjust an effective needle length. An example of such dental needle devices which have effective needle length variable with use of an adjustment expedient is described in Japanese patent No. 882,362 as published under 52-9,950. It is obviously cumbersome to set such an adjustment device on the needle device as inherently required in this type of mode to establish an intended effective needle length by the aid of a further additional utensil, which attachments may restrict an oral space available for surgical treatment. A needle device has been demanded which is handy and easily manipulable and dissolves the above stated problems encountered in operationality with any known devices.